Hello, hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where I'm going to be talking about the neurovasculature of the lower leg and knee.
So what I'm going to be basically doing throughout this tutorial is describing the main blood vessels and also nerves that you see on the lower leg as you see also on these three images.
Now, I'm going to be talking about the different arteries, veins, and nerves that we find on our lower leg—so below… the region below your knee and all the way to your foot.
We’re going to start off with, then, the different arteries that we find on the lower leg, and we’re going to list them. And the ones that we’re going to be including here on this tutorial or seeing on this region of your body are the popliteal artery, the anterior tibial, the anterior lateral and medial malleolar arteries, the inferior lateral and medial genicular arteries, and also, we’re going to be seeing, then, the superior and lateral medial genicular arteries, the posterior tibial artery. We’re going to be seeing this one that can either be called the peroneal artery or the fibular artery.
We’re now ready to move on to the very first one that we saw on that list. And before you ask me, “What is going on on this image?” I'm going to just say that this is the back of your knee with the several muscles that we’re going to be finding here on this region and some of the blood vessels and nerves. And we’re highlighting the artery that we’re going to be briefly talking about, the popliteal artery.
Now, this blood vessel is the continuation of the femoral artery which is the main arterial blood supplier of your leg. It runs from the adductor hiatus, until the lower margin of the popliteal muscle where it divides, then, into the anterior and posterior tibial arteries. And during its course, the popliteal artery gives off several branches that will be, then, covered on the next slides.
We’re going to be turning now the leg onto an anterior view where we’re highlighting this structure here known as the anterior tibial artery. And this artery is one of the two continuations of the popliteal artery and runs from the lower margin of the popliteal muscle ventrally or anteriorly towards the back of your foot, or also known as the dorsum of the foot—a fancier way to call the back of your foot which you partially see here on this image.
Now, at this point, this artery continues as the dorsal artery of the foot. Distally, the anterior tibial artery gives off two branches which we will be talking about or seeing here, highlighted in green. On the left image, we’re looking at the anterior medial malleolar artery. And on the image on the right side, we’re looking at the anterior lateral malleolar artery, some tongue twisters here for me at least.
These arteries are coming out of the anterior tibial artery and start shortly above the ankle joint and run towards the medial and lateral sides of the ankle in order to supply these regions with blood. They also form anastomosis.
Now, just for clarification, this is the medial side of your foot where you have, then… or this is the same direction of the big toe. This is going to be, then, the lateral side where you have your little toe, and you notice how these two malleolar arteries are, then, moving towards the sides of the ankle.
We’re going to now focus here on the anterior medial malleolar artery to say that this one runs below the tendons of the extensor hallucis longus muscle and goes medially where it splits up into many small branches. It forms an anastomosis with the posterior tibial artery and the medial plantar artery.
The next one that we’re going to be now highlighting that we’ve seen on the previous slides, this is, then, the anterior lateral malleolar artery. The lateral one runs below the tendons of the extensor digitorum longus muscle and goes laterally towards the lateral malleolus. Just for a bit of location here, this is then the lateral malleolus.
It forms an anastomosis with the ramus perforans or their perforating branch of the fibular artery and the lateral tarsal artery.
We are going to move on now to a set of different arteries, which are known as the superior and inferior medial and lateral genicular arteries. And as a source of comparison, we’re going to put them altogether. The first one that you see now on the screen, highlighted in green, is known as the superior lateral genicular artery. And keep in mind that we’re looking at the posterior view of the lower leg and knee. You even notice a bit here of the femur and a bit of the tibia as well, and this is where you should see the posterior view of your knee.
The other one that is now seen here, highlighted in green, is then on the other side, and we call it the superior medial genicular artery. And we’re going to find this one also on a posterior view here, which is known as the inferior lateral genicular artery. And now that we just removed here some of the muscles, you can now see clearly the knee joint and where these two are in comparison, then… the superior ones are in comparison to the lower one or the inferior ones.
The other artery is known as the inferior medial genicular artery. So four arteries that we’re going to be discussing next. But you can see them altogether on these images and see how they relate to one another.
These arteries are all branches of the popliteal artery. And the four genicular arteries run towards the four quadrants of the popliteal fossa. They form anastomosis in order to create an arterial network so that good blood flow is granted in this region of your body.
We’re going to, now, pay a little bit more focus here on this one. And if you remember from that collection of images, we’re now looking at the inferior medial genicular artery. This one runs around the medial condyle of the tibia, as you can see here—this is the medial condyle of the tibia—and supplies the proximal part of the tibia and the knee joint partially. This artery forms anastomosis with the superior medial genicular artery and the inferior lateral genicular artery.
And if you look here at the anterior view of the knee, you can clearly see here the anastomosis happening. So this is the inferior medial genicular artery anastomosing with, then, the superior medial genicular artery as well as the inferior lateral genicular artery.
The next one that we saw also on those images, and we’re highlighting here from an anterior view of the knee joint, this is known as the superior medial genicular artery. This one is a small artery that runs cranially from the medial epicondyle around the femur, as you can clearly see here. This is the medial epicondyle of the femur, and you see a positioning of this artery in relation to the femur.
In this area, the artery will be supplying parts of the quadriceps femoris muscle and the knee joint. It also forms several anastomoses including anastomosis with the inferior medial, as you can see here, the inferior medial genicular artery as well as the superior lateral genicular artery.
Next in line is going to be this one that you see here, highlighted in green. Now, we’re looking at the posterior view. If you remember from that list, yes, this one is the inferior lateral genicular artery.
This one runs laterally around the head of the fibula towards the anterior side of the knee joint supplying then the knee like the other genicular arteries. Don’t forget that “genus” means “knee.”
The branches of this artery are going to form anatomosis with the other genicular arteries as well. And you can see also this artery, the inferior lateral genicular artery, from an anterior view, seen here now, highlighted in green.
The last one on that list that we now see also from a posterior view, this is the superior lateral genicular artery. It runs below the tendon of the biceps femoris muscle towards the lateral condyle of the femur, and this is the lateral condyle of the femur, as you can see here.
It supplies parts of the quadriceps femoris muscle and also the knee joint.
As for anastomosis, this artery is going to be anastomosing with the other genicular arteries as well as the lateral circumflex femoral artery.
We’re going to be turning now to a posterior view to, now, highlight this structure, a posterior view of the lower leg and also your foot here. We’re now looking at the posterior tibial artery. And the posterior tibial artery is one of the two continuations of the popliteal artery. Remember from the previous slides, I mentioned that the anterior tibial artery is one of these continuations.
This one begins at the level of the popliteus muscle and runs caudally with the tibial nerve into the deep flexor group of the lower leg. And during its course, it gives off the fibular artery as well as several small branches towards different structures of the lower leg, like the tibia, the medial mallelolus and you can see here—this is the medial malleolus for location—the calcaneous, and the surrounding musculature.
We’re now ready to move on to the next artery here that you see highlighted also from a posterior view: one of the branches of the posterior tibial artery that is known as, then, the fibular artery, also known as the peroneal artery. As I mentioned, this one comes from the posterior tibial artery and runs medially from the fibula towards the foot. During its course, it’s going to give off several branches, several small branches, to then the surrounding muscles.
Now, that we covered the main arteries of the lower leg, it is time for us to move on and talk about the main veins that we find in this region. We’re going to be talking about two: the popliteal vein and also the small saphenous vein.
Let’s start off with the very first one here on the list that you see, now highlighted in green. Again, this is a posterior view of your knee, and we’re looking at the popliteal vein highlighted in green. And just like the popliteal artery, which you can also see here on this image, the popliteal vein lies on the popliteal fossa. It drains blood from the lower leg via the anterior and posterior tibial veins and foot towards, then, the femoral vein. Together with the small saphenous vein, it enters the adductor canal where it becomes, then, the femoral vein. So always remember when we talk about veins, the trajectory here is going back from the extremities all the way to the heart.
The next one that I just mentioned, now seen also highlighted in green, this is known as the small saphenous vein. It is a superficial vein of the lower leg that runs from the lateral edge of the foot below the lateral malleolus towards the dorsal side of the lower leg. Blood in the small saphenous vein is going to then flow into the popliteal vein, as you can also see here. This is the popliteal vein that we just talked about on the previous slide.
The small spahenous vein forms several anastomosis with the deep veins of the leg. And that said, we’re ready to move on to then the main nerves that we find on the lower leg.
We’re going to be talking about the common peroneal or fibular nerve, the superficial and deep peroneal or deep fibular nerves, and also the tibial nerve.
Without keeping you waiting, we’re going to start off with this one that you see here, highlighted in green. Again, we’re looking at the posterior view of the leg or your knee here. And we’re highlighting, then, the common peroneal nerve or also known as the common fibular nerve. The common fibular nerve, about one half the size of the tibial nerve which is, then, derived from the dorsal branches of the fourth and fifth lumbar and also the first and second sacral nerves from the sciatic nerve.
The common peroneal or fibular nerve is going to be innervating the peroneus longus, the peroneus brevis, and the short head of the biceps femoris muscle.
The next one that we’re going to be highlighting here—now, we’re looking at it from an anterior view—this is known as the superficial peroneal or fibular nerve. And the superficial fibular nerve innervates the fibularis longus also known as the peroneus longus, and the fibularis brevis, which we can also call the peroneus brevis muscle.
And the skin over the greater part or the dorsum of the foot will also be innervated by the superficial fibular nerve with the exception of the first web space which is innervated by the deep peroneal nerve.
And we’re, right now, moving on to the next one that you will see from an anterior view. Just talked about it, this is the deep peroneal or fibular nerve. And in the leg, the deep fibular nerve supplies or innervates the muscular branches of the tibialis anterior, the extensor digitorum longus, the fibularis or peroneus tertius, and extensor hallucis longus, and also an articular branch of the ankle joint.
We are going to finish this tutorial talking about this nerve that we’re now seeing from a posterior view of the lower leg and also a bit of the thigh here—and more specifically the knee joint, notice here—and this is known as the tibial nerve. And the tibial nerve is a branch of the sciatic nerve. And this nerve is going to be innervating several structures, several muscles including the gastrocnemius, the politeus, the soleus, the plantaris, the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus—so a lot of muscles being innervated by this important nerve of the lower leg, the tibial nerve.